At a guess, I'd say it's fondant, been rolled very thin, cut into strips, had the edges thinned and then sortof squidged and crumpled and stuck on bit by bit although I've never really seen anything done like that to such an extent. Seriously time consuming but very effective! Maybe someone else has tried it before and is in a better position to help?
That could be a stiff buttercream piped on in layers with maybe a leaf tip?
I guess I'll have to just experiment and see what works :)